| /*- |
| * Copyright (c) 2007 Attilio Rao <attilio@freebsd.org> |
| * Copyright (c) 2001 Jason Evans <jasone@freebsd.org> |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice(s), this list of conditions and the following disclaimer as |
| * the first lines of this file unmodified other than the possible |
| * addition of one or more copyright notices. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice(s), this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
| * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY |
| * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
| * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH |
| * DAMAGE. |
| * |
| * $FreeBSD$ |
| */ |
| |
| #ifndef _BSD_SYS_SX_H_ |
| #define _BSD_SYS_SX_H_ |
| |
| #include <sys/bsd__lock.h> |
| #include <sys/bsd__sx.h> |
| |
| #ifdef _FREEBSD_KERNEL |
| //#include <sys/bsd_pcpu.h> |
| #include <sys/bsd_lock_profile.h> |
| #include <sys/bsd_lockstat.h> |
| #include <machine/bsd_atomic.h> |
| #endif |
| |
| /* |
| * In general, the sx locks and rwlocks use very similar algorithms. |
| * The main difference in the implementations is how threads are |
| * blocked when a lock is unavailable. For this, sx locks use sleep |
| * queues which do not support priority propagation, and rwlocks use |
| * turnstiles which do. |
| * |
| * The sx_lock field consists of several fields. The low bit |
| * indicates if the lock is locked with a shared or exclusive lock. A |
| * value of 0 indicates an exclusive lock, and a value of 1 indicates |
| * a shared lock. Bit 1 is a boolean indicating if there are any |
| * threads waiting for a shared lock. Bit 2 is a boolean indicating |
| * if there are any threads waiting for an exclusive lock. Bit 3 is a |
| * boolean indicating if an exclusive lock is recursively held. The |
| * rest of the variable's definition is dependent on the value of the |
| * first bit. For an exclusive lock, it is a pointer to the thread |
| * holding the lock, similar to the mtx_lock field of mutexes. For |
| * shared locks, it is a count of read locks that are held. |
| * |
| * When the lock is not locked by any thread, it is encoded as a |
| * shared lock with zero waiters. |
| */ |
| |
| #define SX_LOCK_SHARED 0x01 |
| #define SX_LOCK_SHARED_WAITERS 0x02 |
| #define SX_LOCK_EXCLUSIVE_WAITERS 0x04 |
| #define SX_LOCK_RECURSED 0x08 |
| #define SX_LOCK_FLAGMASK \ |
| (SX_LOCK_SHARED | SX_LOCK_SHARED_WAITERS | \ |
| SX_LOCK_EXCLUSIVE_WAITERS | SX_LOCK_RECURSED) |
| |
| #define SX_OWNER(x) ((x) & ~SX_LOCK_FLAGMASK) |
| #define SX_SHARERS_SHIFT 4 |
| #define SX_SHARERS(x) (SX_OWNER(x) >> SX_SHARERS_SHIFT) |
| #define SX_SHARERS_LOCK(x) \ |
| ((x) << SX_SHARERS_SHIFT | SX_LOCK_SHARED) |
| #define SX_ONE_SHARER (1 << SX_SHARERS_SHIFT) |
| |
| #define SX_LOCK_UNLOCKED SX_SHARERS_LOCK(0) |
| #define SX_LOCK_DESTROYED \ |
| (SX_LOCK_SHARED_WAITERS | SX_LOCK_EXCLUSIVE_WAITERS) |
| |
| #ifdef _FREEBSD_KERNEL |
| |
| /* |
| * Function prototipes. Routines that start with an underscore are not part |
| * of the public interface and are wrappered with a macro. |
| */ |
| void sx_sysinit(void *arg); |
| #define sx_init(sx, desc) sx_init_flags((sx), (desc), 0) |
| void sx_init_flags(struct sx *sx, const char *description, int opts); |
| void sx_destroy(struct sx *sx); |
| int _sx_slock(struct sx *sx, int opts, const char *file, int line); |
| int _sx_xlock(struct sx *sx, int opts, const char *file, int line); |
| int _sx_try_slock(struct sx *sx, const char *file, int line); |
| int _sx_try_xlock(struct sx *sx, const char *file, int line); |
| void _sx_sunlock(struct sx *sx, const char *file, int line); |
| void _sx_xunlock(struct sx *sx, const char *file, int line); |
| int _sx_try_upgrade(struct sx *sx, const char *file, int line); |
| void _sx_downgrade(struct sx *sx, const char *file, int line); |
| int _sx_xlock_hard(struct sx *sx, uintptr_t tid, int opts, |
| const char *file, int line); |
| int _sx_slock_hard(struct sx *sx, int opts, const char *file, int line); |
| void _sx_xunlock_hard(struct sx *sx, uintptr_t tid, const char *file, int |
| line); |
| void _sx_sunlock_hard(struct sx *sx, const char *file, int line); |
| #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) |
| void _sx_assert(struct sx *sx, int what, const char *file, int line); |
| #endif |
| #ifdef DDB |
| int sx_chain(struct thread *td, struct thread **ownerp); |
| #endif |
| |
| struct sx_args { |
| struct sx *sa_sx; |
| const char *sa_desc; |
| }; |
| |
| #define SX_SYSINIT(name, sxa, desc) \ |
| static struct sx_args name##_args = { \ |
| (sxa), \ |
| (desc) \ |
| }; \ |
| SYSINIT(name##_sx_sysinit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ |
| sx_sysinit, &name##_args); \ |
| SYSUNINIT(name##_sx_sysuninit, SI_SUB_LOCK, SI_ORDER_MIDDLE, \ |
| sx_destroy, (sxa)) |
| |
| /* |
| * Full lock operations that are suitable to be inlined in non-debug kernels. |
| * If the lock can't be acquired or released trivially then the work is |
| * deferred to 'tougher' functions. |
| */ |
| |
| /* Acquire an exclusive lock. */ |
| static __inline int |
| __sx_xlock(struct sx *sx, struct thread *td, int opts, const char *file, |
| int line) |
| { |
| uintptr_t tid = (uintptr_t)td; |
| int error = 0; |
| |
| if (!atomic_cmpset_acq_ptr(&sx->sx_lock, SX_LOCK_UNLOCKED, tid)) |
| error = _sx_xlock_hard(sx, tid, opts, file, line); |
| else |
| LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_SX_XLOCK_ACQUIRE, |
| sx, 0, 0, file, line); |
| |
| return (error); |
| } |
| |
| /* Release an exclusive lock. */ |
| static __inline void |
| __sx_xunlock(struct sx *sx, struct thread *td, const char *file, int line) |
| { |
| uintptr_t tid = (uintptr_t)td; |
| |
| if (!atomic_cmpset_rel_ptr(&sx->sx_lock, tid, SX_LOCK_UNLOCKED)) |
| _sx_xunlock_hard(sx, tid, file, line); |
| } |
| |
| /* Acquire a shared lock. */ |
| static __inline int |
| __sx_slock(struct sx *sx, int opts, const char *file, int line) |
| { |
| uintptr_t x = sx->sx_lock; |
| int error = 0; |
| |
| if (!(x & SX_LOCK_SHARED) || |
| !atomic_cmpset_acq_ptr(&sx->sx_lock, x, x + SX_ONE_SHARER)) |
| error = _sx_slock_hard(sx, opts, file, line); |
| else |
| LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_SX_SLOCK_ACQUIRE, sx, 0, |
| 0, file, line); |
| |
| return (error); |
| } |
| |
| /* |
| * Release a shared lock. We can just drop a single shared lock so |
| * long as we aren't trying to drop the last shared lock when other |
| * threads are waiting for an exclusive lock. This takes advantage of |
| * the fact that an unlocked lock is encoded as a shared lock with a |
| * count of 0. |
| */ |
| static __inline void |
| __sx_sunlock(struct sx *sx, const char *file, int line) |
| { |
| uintptr_t x = sx->sx_lock; |
| |
| if (x == (SX_SHARERS_LOCK(1) | SX_LOCK_EXCLUSIVE_WAITERS) || |
| !atomic_cmpset_rel_ptr(&sx->sx_lock, x, x - SX_ONE_SHARER)) |
| _sx_sunlock_hard(sx, file, line); |
| } |
| |
| /* |
| * Public interface for lock operations. |
| */ |
| #ifndef LOCK_DEBUG |
| #error "LOCK_DEBUG not defined, include <sys/lock.h> before <sys/sx.h>" |
| #endif |
| #if 0 |
| #if (LOCK_DEBUG > 0) || defined(SX_NOINLINE) |
| #define sx_xlock(sx) (void)_sx_xlock((sx), 0, LOCK_FILE, LOCK_LINE) |
| #define sx_xlock_sig(sx) \ |
| _sx_xlock((sx), SX_INTERRUPTIBLE, LOCK_FILE, LOCK_LINE) |
| #define sx_xunlock(sx) _sx_xunlock((sx), LOCK_FILE, LOCK_LINE) |
| #define sx_slock(sx) (void)_sx_slock((sx), 0, LOCK_FILE, LOCK_LINE) |
| #define sx_slock_sig(sx) \ |
| _sx_slock((sx), SX_INTERRUPTIBLE, LOCK_FILE, LOCK_LINE) |
| #define sx_sunlock(sx) _sx_sunlock((sx), LOCK_FILE, LOCK_LINE) |
| #else |
| #define sx_xlock(sx) //FIXME (void)__sx_xlock((sx), curthread, 0, LOCK_FILE, LOCK_LINE) |
| #define sx_xlock_sig(sx) //FIXME __sx_xlock((sx), curthread, SX_INTERRUPTIBLE, LOCK_FILE, LOCK_LINE) |
| #define sx_xunlock(sx) //FIXME __sx_xunlock((sx), curthread, LOCK_FILE, LOCK_LINE) |
| #define sx_slock(sx) //FIXME (void)__sx_slock((sx), 0, LOCK_FILE, LOCK_LINE) |
| #define sx_slock_sig(sx) //FIXME __sx_slock((sx), SX_INTERRUPTIBLE, LOCK_FILE, LOCK_LINE) |
| #define sx_sunlock(sx) //FIXME __sx_sunlock((sx), LOCK_FILE, LOCK_LINE) |
| #endif /* LOCK_DEBUG > 0 || SX_NOINLINE */ |
| #define sx_try_slock(sx) //FIXME _sx_try_slock((sx), LOCK_FILE, LOCK_LINE) |
| #define sx_try_xlock(sx) //FIXME _sx_try_xlock((sx), LOCK_FILE, LOCK_LINE) |
| #define sx_try_upgrade(sx) //FIXME _sx_try_upgrade((sx), LOCK_FILE, LOCK_LINE) |
| #define sx_downgrade(sx) //FIXME _sx_downgrade((sx), LOCK_FILE, LOCK_LINE) |
| #endif//0 |
| |
| void sx_xlock(struct sx* sx); |
| int sx_xlock_sig(struct sx* sx); |
| void sx_xunlock(struct sx* sx); |
| void sx_slock(struct sx* sx); |
| int sx_slock_sig(struct sx* sx); |
| void sx_sunlock(struct sx* sx); |
| int sx_try_slock(struct sx* sx); |
| int sx_try_xlock(struct sx* sx); |
| int sx_try_upgrade(struct sx* sx); |
| void sx_downgrade(struct sx* sx); |
| |
| /* |
| * Return a pointer to the owning thread if the lock is exclusively |
| * locked. |
| */ |
| #define sx_xholder(sx) \ |
| ((sx)->sx_lock & SX_LOCK_SHARED ? NULL : \ |
| (struct thread *)SX_OWNER((sx)->sx_lock)) |
| |
| #define sx_xlocked(sx) \ |
| (((sx)->sx_lock & ~(SX_LOCK_FLAGMASK & ~SX_LOCK_SHARED)) == \ |
| (uintptr_t)curthread) |
| |
| #define sx_unlock(sx) do { \ |
| if (sx_xlocked(sx)) \ |
| sx_xunlock(sx); \ |
| else \ |
| sx_sunlock(sx); \ |
| } while (0) |
| |
| #define sx_sleep(chan, sx, pri, wmesg, timo) \ |
| _sleep((chan), &(sx)->lock_object, (pri), (wmesg), (timo)) |
| |
| /* |
| * Options passed to sx_init_flags(). |
| */ |
| #define SX_DUPOK 0x01 |
| #define SX_NOPROFILE 0x02 |
| #define SX_NOWITNESS 0x04 |
| #define SX_QUIET 0x08 |
| #define SX_NOADAPTIVE 0x10 |
| #define SX_RECURSE 0x20 |
| |
| /* |
| * Options passed to sx_*lock_hard(). |
| */ |
| #define SX_INTERRUPTIBLE 0x40 |
| |
| #if defined(INVARIANTS) || defined(INVARIANT_SUPPORT) |
| #define SA_LOCKED LA_LOCKED |
| #define SA_SLOCKED LA_SLOCKED |
| #define SA_XLOCKED LA_XLOCKED |
| #define SA_UNLOCKED LA_UNLOCKED |
| #define SA_RECURSED LA_RECURSED |
| #define SA_NOTRECURSED LA_NOTRECURSED |
| |
| /* Backwards compatability. */ |
| #define SX_LOCKED LA_LOCKED |
| #define SX_SLOCKED LA_SLOCKED |
| #define SX_XLOCKED LA_XLOCKED |
| #define SX_UNLOCKED LA_UNLOCKED |
| #define SX_RECURSED LA_RECURSED |
| #define SX_NOTRECURSED LA_NOTRECURSED |
| #endif |
| |
| #ifdef INVARIANTS |
| #define sx_assert(sx, what) _sx_assert((sx), (what), LOCK_FILE, LOCK_LINE) |
| #else |
| #define sx_assert(sx, what) (void)0 |
| #endif |
| |
| #endif /* _FREEBSD_KERNEL */ |
| |
| #endif /* !_BSD_SYS_SX_H_ */ |